This invention relates generally to members whose compliancy increases at elevated temperatures. More particularly, this invention relates to members for fusing by heat and pressure toner particles to a receiver wherein the members include a layer of elastomer incorporating particles of eutectic material which are solid at ambient temperatures but which become fluid at fusing temperatures to effect a change in the compliancy of the member to prevent fuser-related image defects.
In processes involving contact of material by a member, it may be desirable to change the compliancy of the member during the operating cycle in order to prevent process-related defects in the material. For example, in electrographic copiers, toner images formed of thermoplastic toner particles are commonly fused to a receiver by means of pressure and heat applied in the nip of a roller fuser. Toner particles which are loosely held to a receiver prior to fusing must be maintained in their image-wise position during the fusing process so that movement of the particles and consequent image defects in the fused image do not result. Elastomer-covered fuser rollers cause localized stresses in the receiver material as it passes through the roller nip causing distortions in the toner image. Elastomeric layers which are more compliant tend to minimize such nip stresses and thus eliminate fuser-related image defects. Compliancy may be increased by making the elastomeric layers thicker and/or by using an elastomeric foam material. However, since a fuser roller is commonly heated internally, the elastomeric layer must be heat conductive in order to provide the necessary heat to fuse toner images on receivers coming into contact with the fuser roller. Fuser layers made of thick elastomeric layers or foam layers require an inefficient larger heat source to produce the same surface fusing temperature.
It is therefore desirable that a fuser member such as a fuser roller which fuses toner images to a receiver, through the application of heat and pressure, not cause defects in the fused images due to localized stresses produced during the fusing process. It is also desirable that the fuser member be made of a suitable material which permits efficient thermal conduction through the fuser layer when the member is heated internally.